1. Field of the Invention
The present invention relates to an image reading device which uses a linear scanner to read a plurality of frame images while transporting an elongated information carrier on which the frame images are recorded.
2. Description of the Related Art
Recent years have seen the spread of a technology in which an image is formed on a recording material by the following process. Firstly, a frame image recorded on an image information carrier, for example, a photographic film, is photoelectrically read by a line sensor such as a CCD. The digital image data obtained from the reading is then subjected to image processings such as reduction or enlargement or various types of correction. An image is then formed on the recording material using a laser light modulated on the basis of the digital image data obtained after the image processings.
In order to achieve a precise image reading using this technology in which a frame image is digitally read by an area sensor such as a CCD, the frame image first undergoes a preliminary reading (usually called a xe2x80x9cprescanxe2x80x9d) and reading conditions (such as the amount of light irradiated onto the frame image and the charge accumulation time of the CCD) are set in accordance with the density and the like of the frame image. The frame image is then read again under the set reading conditions (called xe2x80x9cfine scanningxe2x80x9d).
However, when the film is the new photographic film provided with a magnetic recording layer (referred to below as xe2x80x9cAPSxe2x80x9d), magnetic information processing tasks (reading and writing) are performed in addition to the image reading. Accordingly, four steps in a film processing series are performed, namely, reading magnetic information from the magnetic recording layer, writing magnetic information to the magnetic recording layer, prescanning using the area sensor, and fine scanning using the area sensor.
When image reading is performed using an area sensor, the transporting of the photographic film has to be stopped at the reading position for each frame in order to read the image frame. However, while the transporting is stopped, writing of the magnetic information cannot be carried out resulting in the image reading and magnetic information processing tasks taking an inconveniently long time.
For this reason, the present inventors attempted to introduce image reading using a line sensor in order to achieve a reduction in the length of time required to read an image and to process magnetic information tasks. More specifically, the prescan and the magnetic information reading are performed during the outward (forward) transporting and the magnetic information writing is performed at the same time as the fine scanning is being performed during the return transporting. This enables the four processings to be completed efficiently in one reciprocal transporting.
At this point, the writing of the magnetic information requires the transporting speed to be constant, however, the transporting speed during fine scanning differs for each image frame on the basis of the reading conditions. Accordingly, if magnetic information writing is started at a transporting speed for fine scanning a particular image frame, then even if the fine scanning of that image is completed, if the writing of the magnetic information is not completed, the magnetic information writing has to be continued at the current transporting speed. As a result of this, when a particular image frame is fine scanned, the image information carrier ends up advancing partway into the next image frame in order to write the magnetic information (referred to below as xe2x80x9coverrunxe2x80x9d). Therefore, it has been necessary to transport the image information carrier in reverse for a predetermined distance before performing fine scanning on the next image frame.
In other words, the structure of a device which performs reading and writing of magnetic information as well as image reading during a reciprocal transportation along the same transporting path is simple, however, the distance of the overrun becomes large if accurate magnetic information processing and image reading are to be carried out, and it is unavoidable that the film image carrier has to be transported in reverse for the distance corresponding to the overrun distance. As a result, in spite of the fact that a line sensor was being used, the long length of time required to read the images of one APS film was a problem.
In consideration of the above, the aim of the present invention is to provide an image reading device capable of making the time taken to transport an image information carrier as short as possible, when magnetic information processing and image reading are performed during the same transporting.
The first aspect of the present invention is an image reading device which transports an elongated image information carrier on which a plurality of image frames are recorded and which is provided with a magnetic recording layer on which is recorded magnetic information, and which reads image information of each image frame, comprising a linear scanner which performs a prescan for preliminarily reading image information of each image frame and which performs a fine scan for reading image information of each image frame under reading condition set on the basis of image information obtained in the prescan, a magnetic information reading and writing section which reads magnetic information on the magnetic recording layer during the prescan and writes magnetic information during the fine scan, and transporting means which transports the image information carrier during the prescan along a transporting path at a constant speed and which, for each image frame, transports the image information carrier during the fine scan along the transporting path at a speed set for each image frame in accordance with the reading condition and transports the image information carrier in a reverse direction of a transporting direction of the fine scan by a predetermined amount, wherein the writing of the magnetic information of each image frame is performed after the transporting speed of the image information carrier has converged to within a predetermined range with regard to the transporting speed for fine scanning set for each image frame.
According to the first aspect of the present invention, it is possible to start the writing of the magnetic information of an image frame after the transporting speed of an image information carrier has converged to within a predetermined range with respect to the transporting speed for fine scanning set for an image frame (either the image frame being fine scanned or another image frame). In this case, because the magnetic information writing requires the transporting speed to converge to within a predetermined range on either side of a constant speed, if the magnetic information writing takes longer than the fine scan, the image information carrier ends up being transported to a position partway into the next image frame at the transporting speed for fine scanning set by the reading conditions (called xe2x80x9coverrunxe2x80x9d below). However, in the present invention, because it is possible to perform the image information writing after transporting speed of the image information carrier has converged to within a predetermined range with regard to the transporting speed for fine scanning, namely, because it is possible to perform the image information writing prior to the fine scanning, the distance of the overrun can be controlled to a minimum. Accordingly, the processing time required for the image information carrier can be made as short as possible.
Note that because the image information carrier is transported at a constant speed during the prescan, the reading of the magnetic information can be performed at the same time.
The second aspect of the present invention is an image reading device according to the first aspect of the present invention in which the magnetic information reading and writing section is disposed at a position where, at the same time as the linear scanner starts the fine scanning of one of the image frames, the writing of magnetic information for one of the image frames can be started.
According to the second aspect of the present invention, at the same time as the linear scanner starts performing the fine scanning of an image frame, the magnetic information reading and writing section can start performing magnetic information writing for an image frame (either for another image frame or the image frame being fine scanned). Accordingly, the writing of the magnetic information can be performed after the transporting speed of the image information carrier has definitely converged to within a predetermined range.
The third aspect of the present invention is an image reading device according to the first or second aspect of the present invention in which a distance between a writing position where magnetic information writing is performed on the image information carrier by the magnetic information reading and writing section and a reading position where image reading is performed on the image information carrier by the linear scanner is an integral multiple of a pitch of the image frame.
According to the third aspect of the present invention, for example, when the fine scanning of a particular frame image is started, the writing of the magnetic information of the next frame image to the magnetic recording layer of the next frame image can be started. Accordingly, the writing of the magnetic information can be started at the same time of performing the fine scan, and the processing time can be reduced.
The fourth aspect of the present invention is an image reading device according to the first, second or third aspect of the present invention, in which the transporting of the image information carrier is stopped at the same time as the fine scanning of each image frame by the linear scanner and the writing of the magnetic information for each image frame have been completed.
In which the transporting of the image information carrier is stopped after the fine scanning of an image frame by the linear scanner and the writing of the magnetic information have been completed.
According to the fourth aspect of the present invention, by stopping the transporting of the image information carrier immediately after the fine scanning of an image and the writing of magnetic information have been completed, the overrun distance can be controlled to a minimum.